The preserved expression of neuropilin (NRP) 1 contributes to a better prognosis in colon cancer.

Vascular endothelial growth factor A (VEGF-A) plays an essential role in tumor progression through stromal neovascularization in malignant solid tumors. Neuropilin (NRP) is considered to be the specific receptor for limited types of VEGF-A isoform, VEGF165. The clinicopathological implications of NRP are not well understood in colon cancer, while almost all colon cancers overexpressed VEGF-A. We examined the expression levels of NRP1 and NRP2 genes in 54 colon cancer cases and paired extraneoplastic tissue with quantitative real-time polymerase chain reaction. The gene expression levels of NRP1 in the tumor (0.431+/-0.583) were significantly decreased compared to those in the extraneoplastic tissue (0.754+/-0.799) (paired t-test, p=0.0208). On the other hand, the gene expression levels of NRP2 in the tumor (0.763+/-0.791) were not decreased compared to those in the extraneoplastic tissue (0.508+/-0.386) (paired t-test, p=0.0511). Twenty cases, with preserved expression of the NRP1 gene in the tumor, showed a better prognosis as compared to the 34 cases with decreased NRP1 expression (p=0.0258, log-rank test). No significant relationship was noted between NRP2 gene expression and prognosis. The results suggested that preserved NRP1 expression provides colon cancer patients with a better prognosis.